Radio Frequency Identification (“RFID”) technology has been around for many years, but in the past few years there has been a surge in its acceptance and a massive growth in its use. RFID technology generally involves the use of an interrogator to transmit an RF signal to a transponder in order to interrogate the transponder and obtain data stored therein. After receiving the interrogating RF signal, the transponder answers to the inquiry by backscattering or transmitting a responsive RF communication which contains the requested data.
RFID technology lends itself extremely well for use in asset tracking (e.g., tracking merchandise in retail environments or warehouses). Such an RFID tracking system, having a plurality of interrogators and a plurality of transponders placed on tracked objects, could be used to obtain information on the tracked objects' location or other status related data. However, this system requires installation of multiple interrogators around the trackable area. This results in a dense population of RFID interrogators. In addition, it has been a common practice in the art to have the interrogators constantly interrogating the transponders. However, the constant RF transmissions create RF interference between interrogators, thereby reducing interrogator performance and making them less effective at reading transponders.
There is a limited solution of reducing interference in order to improve interrogator productivity. One method involves using a triggering network that includes triggers connected to the interrogators using wired or wireless networks. The triggers activate the interrogators at appropriate times so that they only read the transponders at those specified times. Although this system improves reading productivity, it also adds complexity and cost to the overall system. Part of the additional cost is the implementation of additional equipment required to properly interface (e.g., hardware and/or software for a communication protocol) triggering devices with the RFID interrogators.
In addition, both wired and wireless communications in the triggering networks suffer from deficiencies. Wired networks require installation of obtrusive wiring and involve significant expense. Wireless networks suffer from similar limitations. Since most common wireless networks (e.g., IEEE 802.11 protocols, Bluetooth, etc.) use an out-of-band RF signals, than RFID interrogators, such networks require installation or integration of complimentary receivers and transceivers on the triggers and the interrogators. In addition, wireless networks have a high total cost of ownership due to the complexity of managing, administering, and diagnosing the network. Therefore, there is a need for a trigger network that is based on the RF communication medium native to the interrogators.